Many investigators at Yale University (Medical School and College) have a long-standing interest in musculoskeletal disorders. These investigators represent numerous departments and discjplines. This interest in the pathophysiology of the skeleton has created a number of collaborative projects among interested investigators. As a result of these interactions, investigators have sought to develop cell culture techniques within their own laboratories often leading to expensive duplication of already existing technologies. Although standard techniques are available, intra-laboratpry variation in the quality and number of cells is unavoidable. This variation is exacerbated by the difficulties in isolating bone cells from the myriad of genetically engineered murine models now available. To address this Institutional need, the Cell Core was developed as part of the initial application of the YCCMD. It remains one of the five major components of the Center. As part of the Cell Core's new initiatives, isolation of adipocyte precursors and adipocyte differentiation protocols are now available. In addition, murine mesenchymal stem cells may be obtained through the Cell Core. The goal of the Cell Core is to facilitate the experimental use of authentic primary, isolated mouse and rat osteoblasts, osteoclast-like cells generated in vitro, osteoblast precursors, and bone marrow-derived adipocytes. As part of our imaging initiative, the Cell Core has expanded its services to include small animal high-resolution radiographs. The new Specific Aims of the proposal are to provide the following services: 1. Isolate and culture primary murine and fetal rat calvarial osteoblasts. This includes large-scale preparations for biochemical analyses and RNA and DMA purification. 2. Differentiate murine osteoclast-like cells from bone marrow or spleen cells by: a) in vitro coculture with osteoblasts or induction with Oncostatin-M or parathyroid hormone;b) culture with MCSF and RANKL. 3. Grow and differentiate mouse bone marrow derived osteoblast/adipocyte progenitors (marrow stromal cells) 4. Supply primary mouse mesenchymal stem cells (MSCs). 5. Support a cell bank that provides access to a large number of cryoperserved cell lines. 6. Provide small animal bone densitometry (DXA) and radiographs. 7. Train investigators for in vitro isolation and culture of osteoblasts, osteoclasts and progenitor cells, so that investigators appropriately trained can establish these techniques in their laboratories The Core will provide cells to Center members in a coordinated manner, such that expenses and duplication of effort are minimized. The Cell Core will also provide support to the Pilot and Feasibility Projects as part of our continuing effort to attract new investigators to musculoskeletal research. The Core has an established